title: Glucuronoxylomannan from Cryptococcus neoformans down-regulates the enzyme 6-phosphofructo-1-kinase of macrophages.
abstract: The encapsulated yeast Cryptococcus neoformans is the causative agent of cryptococosis, an opportunistic life-threatening infection. C. neoformans is coated by a polysaccharide capsule mainly composed of glucuronoxylomannan (GXM). GXM is considered a key virulence factor of this pathogen. The present work aimed at evaluating the effects of GXM on the key glycolytic enzyme, 6-phosphofructo-1-kinase (PFK). GXM inhibited PFK activity in cultured murine macrophages in both dose- and time-dependent manners, which occurred in parallel to cell viability decrease. The polysaccharide also inhibited purified PFK, promoting a decrease on the enzyme affinity for its substrates. In macrophages GXM and PFK partially co-localized, suggesting that internalized polysaccharide directly may interact with this enzyme. The mechanism of PFK inhibition involved dissociation of tetramers into weakly active dimers, as revealed by fluorescence spectroscopy. Allosteric modulators of the enzyme able to stabilize its tetrameric conformation attenuated the inhibition promoted by GXM. Altogether, our results suggest that the mechanism of GXM-induced cell death involves the inhibition of the glycolytic flux.
authors.affiliation: Laboratório de Enzimologia e Controle do Metabolismo, Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-590, Brazil.
authors.forename: Juliana
authors.initials: J
authors.lastname: Grechi
authors.forename: Monica
authors.initials: M
authors.lastname: Marinho-Carvalho
authors.forename: Patricia
authors.initials: P
authors.lastname: Zancan
authors.forename: Leonardo Paes
authors.initials: LP
authors.lastname: Cinelli
authors.forename: Andre M O
authors.initials: AM
authors.lastname: Gomes
authors.forename: Marcio L
authors.initials: ML
authors.lastname: Rodrigues
authors.forename: Leonardo
authors.initials: L
authors.lastname: Nimrichter
authors.forename: Mauro
authors.initials: M
authors.lastname: Sola-Penna
mesh_terms: D000494:Allosteric Regulation; D000818:Animals; D016923:Cell Death; D002478:Cells, Cultured; D003455:Cryptococcus neoformans / Q000472:pathogenicity*; D015536:Down-Regulation / Q000187:drug effects; D006019:Glycolysis; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D010732:Phosphofructokinase-1 / Q000037:antagonists & inhibitors*; D011134:Polysaccharides / Q000494:pharmacology*; D055503:Protein Multimerization / Q000187:drug effects; D055550:Protein Stability / Q000187:drug effects
chemical_list: D011134:Polysaccharides; C027478:glucuronoxylomannan; D010732:Phosphofructokinase-1; C068652:1-phosphofructokinase